Of course, the myths aren’t all psychological…..

You may have been reading about the Home Secretary’s embarrassing blunder over the ‘criminal can’t be deported because he had a cat’ myth.
Here’s a breakdown, which points out that it’s a myth that’s been around for some time, and it derives from misleading headlines in newspaper articles:http://www.guardian.co.uk/politics/reality-check-with-polly-curtis/2011/oct/04/reality-check-cat-theresa-may – and also shows that even though there’s lots of disconfirming evidence and information it doesn’t go away – just like lots of myths in psychology.
You could try to do the ‘why do we believe these things?’ analysis for yourself on this one – though you will need to assume some racism or at least xenophobia in the people who keep it going.

Footnote: why are these people so worried about human rights that they have to use lies to argue against them?